Composition for activation energy rays and method of forming pattern

ABSTRACT

A composition for activation energy rays comprising a specific vinyl ether group-containing compound (A) in which a vinyl ether group is bonded to a secondary or tertiary carbon atom, a polymer (B) having a carboxyl group and/or a hydroxyphenyl group, and a photo-acid generator compound (C) can form a resist pattern having an excellent sensitivity without carrying out any heat treatment at a temperature of 60° C. or more after irradiation.

TECHNICAL FIELD

The present invention relates to a composition for activation energyrays and a method of forming a pattern by the use of the composition,and more particularly, it relates to a method of forming a positivepattern useful for circuit formation of electronic devices, materialsfor printing, and the like.

BACKGROUND ART

Currently, positive photoresists are widely used for formation ofcircuit patterns of electronic devices or the like. As positivephotoresist compositions which can be used for these applications,combinations of alkali-soluble novolac resins and quinone diazidecompounds as sensitizers have often been used.

In this kind of composition, there is utilized a reaction in which aquinone diazide group is photolyzed by irradiation with ultraviolet raysto form indenecarboxylic acid via ketene. However, in the resist formedby using the quinone diazide compound, a resolution is insufficientsometimes in a case where it is necessary to form a very fine pattern.

On the other hand, Japanese Patent Application Laid-open No. 295064/1994discloses a photosensitive composition comprising a carboxylgroup-containing polymer, a compound containing two or more vinyl ethergroups in one molecule, and a compound which generates an acid whenirradiated with activation energy rays. When a film formed from thiscomposition is heated (primary heating), a polycarboxylic acid resin iscross-linked by an addition reaction between a carboxyl group and avinyl ether group, so that the film becomes insoluble in a solvent or anaqueous alkaline solution. Furthermore, when the film is further heated(secondary heating) after the irradiation with the activation energyrays, the cross-linked structure is cleaved owing to a catalytic actionof the acid generated by the activation energy rays irradiation, so thatthe irradiated portion becomes soluble in the solvent or the aqueousalkaline solution again. Then, the irradiated portion is removed bydevelopment to form a resist pattern.

The above-described method, in which the circuit pattern is formed byheating the photosensitive composition comprising the polycarboxylicacid resin, the polyfunctional vinyl ether compound and the compoundwhich generates the acid when irradiated with the activation energyrays, can basically satisfy a request for the formation of the very finecircuit pattern in recent years. However, in order to cleave thecross-linked structure of the irradiated portion after the activationenergy rays irradiation, the heating process is essential, and it isrequired that the heating process is carried out at 60 to 150° C. for 10to 60 minutes. The addition of such a heating process (secondaryheating) decreases a production speed in a pattern formation process andfurther may cause another problem such as deformation of a substrateowing to the heating at high temperature. Furthermore, since the acidcomponent generated by the light irradiation diffuses in the resist filmowing to the secondary heating, there is also another problem that theresist film having the excellent resolution cannot be obtained.

DISCLOSURE OF THE INVENTION

Therefore, it is an object of the present invention to provide acomposition for activation energy rays capable of forming a stablepositive resist pattern having an excellent sensitivity and resolutionwithout requiring any heating step under high temperature conditionsafter irradiation with activation energy rays, as well as a method offorming a pattern by the use of the composition.

The present inventors have made extensive investigation to achieve theobject, and as a result, they have found that a stable positive resistpattern having an excellent sensitivity and resolution can be formedwithout requiring a secondary heat treatment at a high temperature suchas 60° C. or higher after irradiation with activation energy rays by theuse of a composition for activation energy rays containing, as essentialcomponents, a specific vinyl ether group-containing compound, and apolymer having a specific amount of a carboxyl group and/or ahydroxyphenyl group and a specific number-average molecular weight andglass transition temperature, and in consequence, the present inventionhas been completed.

That is, the present invention is directed to the following aspects:

-   (1) A composition for activation energy rays, comprising, as    essential components,    -   at least one vinyl ether group-containing compound (A) selected        from the group consisting of a monovinyl ether compound        represented by the following formula (1):

-   -    (wherein R is a hydrocarbon bond, a carbon ring structure, a        combination bond of a carbon ring structure and a hydrocarbon        bond, an aromatic heterocyclic structure, or a combination bond        of an aromatic heterocyclic structure and a hydrocarbon bond in        which an initial atom of R bonded to an ether bond is a        secondary or tertiary carbon atom), and    -   a polyvinyl ether compound represented by the following formula        (2):

-   -    [wherein R¹ is a carbon ring structure, a combination bond of a        carbon ring structure and a hydrocarbon bond, an aromatic ring        structure, an aromatic heterocyclic structure, a combination        bond of an aromatic ring structure and a hydrocarbon bond, a        combination bond of an aromatic heterocyclic structure and a        hydrocarbon bond, or a hydrocarbon bond having 1 to 24 carbon        atoms; A¹ and A² are each a group represented by the following        formula (a):

-   -    (wherein R² is independently a monovalent hydrocarbon group        with 1 to 24 carbon atoms which may have a carbon ring        structure, an aromatic ring structure or a heterocyclic        structure, and at least an element at a substitution site of R²        is a carbon atom; R³, R⁴ and R⁵ are each independently a        monovalent hydrocarbon group with 1 to 24 carbon atoms which may        have a carbon ring structure, an aromatic ring structure or a        heterocyclic structure, or a hydrogen atom; and q is 0 or 1,        provided that when R¹ is a hydrocarbon bond having 1 to 24        carbon atoms, both of q's in A¹ and A² are 1, and when q is 0,        an atom of R¹ bonded to A¹ or A² is a secondary or tertiary        carbon atom); and A³ is a group represented by the following        formula (b):

-   -    (wherein R² to R⁵ are the same as R² to R⁵ defined in the        formula (a)); and p is an integer of 0 to 2]; and        -   at least one polymer (B) selected from the group consisting            of the following polymers (a) to (c);        -   (a) a polymer containing 0.5 to 10 equivalents of a carboxyl            group per kg of the polymer, and having a number-average            molecular weight in a range of 3,000 to 100,000 and a glass            transition temperature of 0° C. or higher,        -   (b) a polymer containing at least 1 to 10 equivalents of a            hydroxyphenyl group per kg of the polymer, and having a            number-average molecular weight in a range of 500 to 100,000            and a glass transition temperature of 0° C. or higher, and        -   (c) a polymer containing at least 0.2 to 20 equivalents of a            hydroxyphenyl group and a carboxyl group per kg of polymer,            and having a number-average molecular weight in a range of            500 to 100,000 and a glass transition temperature of 0° C.            or higher.

-   (2) The composition for activation energy rays according to the    paragraph (1), wherein the vinyl ether group-containing compound (A)    is cyclohexyl vinyl ether.

-   (3) The composition for activation energy rays according to the    paragraph (1), wherein the vinyl ether group-containing compound (A)    is a polyvinyl ether compound represented by the following formula:

-   (4) The composition for activation energy rays according to the    paragraph (1), wherein the vinyl ether group-containing compound (A)    is a polyvinyl ether compound represented by the following formula:

-   (5) The composition for activation energy rays according to any one    of the paragraphs (1) to (4), further comprising a photo-acid    generator compound (C).-   (6) The composition for activation energy rays according to the    paragraph (5), which contains 5 to 150 parts by weight of the vinyl    ether group-containing compound (A) with respect to 100 parts by    weight of the polymer (B), and 0 to 40 parts by weight of the    photo-acid generator compound (C) with respect to 100 parts by    weight of the total amount of the polymer (B) and the vinyl ether    group-containing compound (A).-   (7) A method of forming a pattern, comprising:    -   a step of applying the composition for activation energy rays        onto a substrate;    -   a step of heating the substrate;    -   a step of irradiating the substrate with activation energy rays        for patterning;    -   a step of carrying out no heat treatment or carrying out a heat        treatment at a temperature less than 60° C. after the        irradiation; and    -   a step of developing the substrate with a basic developer.-   (8) A method of forming a pattern, comprising:    -   a step of applying the composition for activation energy rays        onto a transparent support film capable of transmitting        activation energy rays, and drying it to form a film layer of        the composition for activation energy rays as a dry film resist        for activation energy rays;    -   a step of press-bonding the film layer of the composition for        activation energy rays as the dry film resist onto a substrate        on which a pattern is to be formed;    -   a step of heating the substrate;    -   a step of irradiating the film layer with activation energy rays        through the support film for patterning;    -   a step of carrying out no heat treatment or carrying out a heat        treatment at a temperature less than 60° C. after irradiation;        and    -   a step of removing the support film and developing the substrate        with a basic developer.-   (9) A method of forming a pattern, comprising:    -   a step of applying the composition for activation energy rays        onto a transfer film, and drying it to form a film layer of the        composition for activation energy rays as a transfer film        resist;    -   a step of press-bonding the film layer of the composition for        activation energy rays as the transfer film resist onto a        substrate on which a pattern is to be formed;    -   a step of heating the substrate;    -   a step of removing the transfer film;    -   a step of irradiating the film layer with activation energy rays        for patterning;    -   a step of carrying out no heat treatment or carrying out a heat        treatment at a temperature less than 60° C. after irradiation;        and    -   a step of developing the substrate with a basic developer.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail.

First, a composition of the present invention will be descried.

Vinyl Ether Group-Containing Compound (A):

A vinyl ether group-containing compound (A) which is an essentialcomponent of a composition of the present invention is a compound inwhich a vinyl ether group is bonded to a secondary or tertiary carbon.In particular, the vinyl ether group-containing compound is preferablyeither a monovinyl ether compound represented by the following formula(1):

(wherein R is a hydrocarbon bond, a carbon ring structure, a combinationbond of a carbon ring structure and a hydrocarbon bond, an aromaticheterocyclic structure, or a combination bond of an aromaticheterocyclic structure and a hydrocarbon bond in which an initial atomof R bonded to the ether bond is a secondary or tertiary carbon atom),or a polyvinyl ether compound represented by the following formula (2):

[wherein R¹ is a carbon ring structure, a combination bond of a carbonring structure and a hydrocarbon bond, an aromatic ring structure, anaromatic heterocyclic structure, a combination bond of an aromatic ringstructure and a hydrocarbon bond, a combination bond of an aromaticheterocyclic structure and a hydrocarbon bond, or a hydrocarbon bondhaving 1 to 24 carbon atoms; A¹ and A² are each a group represented bythe following formula (a):

(wherein R² is independently a monovalent hydrocarbon group with 1 to 24carbon atoms which may have a carbon ring structure, an aromatic ringstructure, or a heterocyclic structure, and at least an element at asubstitution site is a carbon atom; R³, R⁴ and R⁵ are each independentlya monovalent hydrocarbon group with 1 to 24 carbon atoms which may havea carbon ring structure, an aromatic ring structure or a heterocyclicstructure, or a hydrogen atom; and q is 0 or 1, provided that when R¹ isa hydrocarbon bond having 1 to 24 carbon atoms, q in each of A¹ and A²is 1, and when q is 0, an atom of R¹ bonded to A¹ or A² is a secondaryor tertiary carbon atom); A³ is a group represented by the followingformula (b):

(wherein R² to R⁵ are the same as R² to R⁵ defined in the formula (a));and p is an integer of 0 to 2].

In the formula (1), examples of a hydrocarbon group represented by Rinclude groups each having a secondary or tertiary carbon atom, such asan isopropyl group, a 1-methylpropyl group, a 1-methylbutyl group, a1-methylpentyl group, a 1-methylhexyl group, a 1-methylheptyl group, a1-methyloctyl group, a 1-methyldecanyl group, a 1-methyldodecanyl group,a 1-ethylpropyl group, a 1-ethylbutyl group, a 1-ethylpentyl group, a1-ethylhexyl group, a 1-ethylheptyl group, a 1-ethyloctyl group, a1-ethyldecanyl group, a 1-ethyldodecanyl group, a t-butyl group, a1,1-dimethylpropyl group, a 1,1-dimethylbutyl group, a1,1-dimethylpentyl group, a 1,1-dimethylhexyl group, a1,1-dimethylheptyl group, a 1,1-dimethyloctyl group, a1,1-dimethyldecanyl group, and a 1,1-dimethyldodecanyl group.

Examples of a carbon ring structure include a cyclopropyl group, acyclobutyl group, a cyclopentyl group, a cyclohexyl group, and acyclooctyl group.

Examples of an aromatic heterocyclic structure include pyrans, pyrones,pyrroles, pyrrolines, pyrrolidines, imidazolines, imidazolidines,pyrazolidines, piperidines, piperazines, morpholines, indolines, andchromans.

A combination bond of the carbon ring structure and the hydrocarbongroup, or a combination bond of the aromatic heterocyclic structure andthe hydrocarbon group may also be employed, wherein an atom at thebonding site of the vinyl ether group should be a secondary or tertiarycarbon atom.

Among them, the carbon ring structure is preferable, and a cyclohexylgroup is particularly preferable.

In the formula (2), examples of a monovalent hydrocarbon group having 1to 24 carbon atoms represented by R², R³, R⁴ or R⁵ include a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, aheptyl group, an octyl group, a decanyl group, and a dodecanyl group.These groups may be straight or branched. Examples of a carbon ringstructure include a cyclohexyl group and a phenyl group. Examples of aheterocyclic structure include pyrans, pyrones, pyrroles, pyrrolines,pyrrolidines, imidazolines, imidazolidines, pyrazolidines, piperidines,piperazines, morpholines, indolines, and chromans.

Further, in the formula (2), examples of a carbon ring structurerepresented by R¹ include a cyclohexyl group and a phenyl group.Examples of a combination bond of a carbon ring structure and ahydrocarbon bond include a bisphenol residue. Examples of a heterocyclicstructure include pyrans, pyrones, pyrroles, pyrrolines, pyrrolidines,imidazolines, imidazolidines, pyrazolidines, piperidines, piperazines,morpholines, indolines, and chromans.

When R¹ is a hydrocarbon bond having 1 to 24 carbon atoms, q in each ofA¹ and A² is 1, and when q is 0, an atom of R¹ bonded to A¹ or A² is asecondary or tertiary carbon atom.

Examples of the compound represented by the formula (2) include thefollowing compounds:

Polymer (B):

Carboxyl Group-Containing Polymer (a):

A carboxyl group-containing polymer (a) is a film-formable polymercontaining at least one carboxyl group in one molecule. Examples of sucha polymer include: a homopolymer of a carboxyl group-containingpolymerizable unsaturated monomer; a copolymer of the carboxylgroup-containing monomer and another copolymerizable monomer; a resin ofpolyester type, polyurethane type, or polyamide type having a carboxylgroup in the molecular chain or at the molecular end.

Examples of the carboxyl group-containing polymerizable unsaturatedmonomer include acrylic acid, methacrylic acid, crotonic acid, anditaconic acid. Examples of another monomer copolymerizable with such acarboxyl group-containing monomer include: C₁ to C₁₂ alkyl esters of(meth)acrylic acid, such as methyl (meth)acrylate, ethyl (meth)acrylate,propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, anddecyl (meth)acrylate; C₂ to C₆ hydroxyalkyl esters of (meth)acrylicacid, such as hydroxyethyl (meth)acrylate, 2-hydroxypropyl(meth)acrylate, 3-hydroxypropyl (meth)acrylate, and hydroxybutyl(meth)acrylate; vinyl aromatic compounds such as styrene,α-methylstyrene, and p-tert-butylstyrene; vinyl acetate;(meth)acrylonitrile; (meth)acrylamide; and vinylpyrrolidone. Thesemonomers can be used singly or in combination of two or more. Inparticular, vinyl aromatic compounds such as styrene, α-methylstyrene,and C₁ to C₆ alkyl substituted styrene (e.g., p-tert-butylstyrene) arepreferably used as another monomer in terms of the precision of formedimage patterns or resistance to etching.

The polymer (a) preferably has a number-average molecular weight in arange of about 3,000 to 100,000, particularly about 5,000 to 30,000. Apreferred range of the carboxyl group content of the polymer (a) isusually 0.5 to 10 equivalents, particularly 0.5 to 5.0 equivalents perkg of polymer. If the carboxyl group content is less that 0.5equivalent/kg, the cross-linking degree of a film formed by heatingbefore irradiation with activation rays tends to become insufficient,and developability tends to lower due to decreased solubility of theexposed portions in an alkaline developer. On the other hand, if thecarboxyl group content exceeds 10 equivalents/kg, the storage stabilityof the composition tends to lower.

Further, the polymer (a) preferably has a glass transition temperature(Tg) of 0° C. or higher, particularly in a range of 5 to 70° C. If theTg is less than 0° C., an obtained coating film has adhesiveness andtherefore dust and dirt easily adhere to the film so that the handlingof the film tends to be difficult.

Hydroxyphenyl Group-Containing Polymer (b):

A polymer (b) is a polymer containing at least one hydroxyphenyl groupin one molecule. Examples of such a polymer (b) include: a condensationproduct of a monofunctional or polyfunctional phenol compound, analkylphenol compound, or their mixture, with a carbonyl compound such asformaldehyde or acetone; a homopolymer of a hydroxyl group-containingvinyl aromatic compound such as p-hydroxystyrene; and a copolymer of thehydroxyl group-containing vinyl aromatic compound and anothercopolymerizable monomer.

Examples of the monofunctional or polyfunctional phenol compound includecompounds each having 1 to 3 hydroxyl groups on the benzene ring, suchas phenol, o-cresol, m-cresol, p-cresol, 3,5-xylenol, 2,6-xylenol,2,4-xylenol, catechol, resorcin, pyrogallol, and bisphenol A. Examplesof the alkylphenol compound include alkylphenol compounds each having 1to 10 carbon atoms, preferably 1 to 4 carbon atoms in the alkyl moiety,such as p-isopropylphenol, p-tert-butylphenol, p-tert-aminophenol, andp-tert-octylphenol.

The condensation reaction between these compounds and the carbonylcompound such as formaldehyde or acetone can be carried out by a knownmethod in itself. In general, condensation in the presence of an alkalicatalyst provides a resole type resin which becomes insoluble andinfusible with the progress of condensation, and condensation in thepresence of an acid catalyst provides a soluble and fusible novolac typeresin.

In the present invention, the latter novolac type phenol resin canusually be used. Although the molecular weight of the novolac typephenol resin increases with the progress of condensation, in usual, anovolac type phenol resin having a molecular weight of 500 to 2,000obtained by carrying out condensation for 1 to 3 hours is preferablyused. As another monomer copolymerizable with the hydroxylgroup-containing vinyl aromatic compound, another copolymerizablemonomer which is the same as that mentioned for the copolymer as thepolymer (a) can be used.

In usual, the hydroxyphenyl group-containing polymer (b) preferably hasa number-average molecular weight in a range of about 500 to 1,000,000,particularly about 1,000 to 30,000. A preferred range of thehydroxyphenyl group content of the polymer (b) is usually 1.0 to 10equivalents, particularly 2.0 to 8.0 equivalents per kg of polymer. Ifthe hydroxyphenyl group content is less than 1.0 equivalent/kg, thedegree of cross-linking of a film formed by heating before irradiationwith activation rays tends to be insufficient. On the other hand, if thehydroxyphenyl group content exceeds 10 equivalents/kg, an obtainedresist film tends to be brittle.

The polymer (b) preferably has a glass transition temperature (Tg) of 0°C. or higher, particularly in a range of 5 to 70° C., similarly to thepolymer (a). If the Tg is less than 0° C., an obtained coating film hastackiness and therefore dust and dirt easily adhere to the film so thatthe handling of the film tends to be difficult.

Carboxyl Group and Hydroxyphenyl Group-Containing Polymer (c):

A polymer (c) is a film-formable polymer containing at least onecarboxyl group and hydroxyphenyl group in one molecule. Examples of sucha polymer (c) include: a copolymer of hydroxystyrene such asp-hydroxystyrene and a carboxyl group-containing polymerizableunsaturated monomer; and a copolymer of the hydroxystyrene, the carboxylgroup-containing monomer and another copolymerizable monomer.

Examples of the carboxyl group-containing polymerizable unsaturatedmonomer include acrylic acid, methacrylic acid, crotonic acid, itaconicacid and the like. Examples of another copolymerizable monomer include:C₁ to C₁₂ alkyl esters of (meth)acrylic acid, such as methyl(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl(meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl(meth)acrylate, nonyl (meth)acrylate, and decyl (meth)acrylate; C₂ to C₆hydroxyalkyl esters of (meth)acrylic acid, such as hydroxyethyl(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl(meth)acrylate, and hydroxybutyl (meth)acrylate; vinyl aromaticcompounds such as styrene, α-methylstyrene, and p-tert-butylstyrene;vinyl acetate; (meth)acrylonitrile; (meth)acrylamide; andvinylpyrrolidone. These monomers can be used singly or in combination oftwo or more. Further, as the polymer (c), phenol carboxylic acids suchas hydroxybenzoic acid, gallic acid, and resorcylic acid; and a polymerobtained by condensation of formaldehyde with a mixture of the phenolcarboxylic acids with one or two or more of phenols selected fromphenol, C₁ to C₁₈ mono- or dialkyl-substituted phenol or naphthols,resorcinol, and catechol can be used.

In usual, the polymer (c) preferably has a number-average molecularweight in a range of about 500 to 100,000, particularly about 1,500 to30,000. A preferred range of the carboxyl group content of the polymer(c) is usually 0.5 to 10 equivalents, particularly 0.5 to 5.0equivalents per kg of polymer, and a preferred range of thehydroxyphenyl group content of the polymer (c) is at least 1.0equivalent, particularly 2.0 to 8.0 equivalents per kg of polymer. Ifthe carboxyl group content is less than 0.5 equivalent/kg, the degree ofcross-linking of a film formed by heating before irradiation withactivation rays is not sufficient, and developability tends to lower dueto decreased solubility of the exposed portions in an alkalinedeveloper. On the other hand, if the carboxyl group content exceeds 10equivalents/kg, the storage stability of the composition tends to lower.If the hydroxyphenyl group content is less than 1.0 equivalent/kg, thereis case that the degree of cross-linking at cross-linking is notsufficient.

Further, the polymer (c) preferably has a glass transition temperature(Tg) of 0° C. or higher, particularly in a range of 5 to 70° C. If theTg is less than 0° C., an obtained coating film has tackiness andtherefore dust and dirt easily adhere to the film so that the handlingof the film tends to be difficult.

Photo-Acid Generator Compound (C):

A compound (C) generates an acid when irradiated with activation energyrays. Specifically, the compound (hereinafter also referred to as a“photo-acid generating compound”) is decomposed by irradiation withactivation energy rays which will be described below and generates anacid having an intensity sufficient to cleave the cross-linked structureformed between the polymer (B) and the compound (A). As such a compound,conventionally known compounds can be used.

Examples of compounds and mixtures thereof to be used as the photo-acidgenerator include: diazonium, phosphonium, sulfonium, and iodoniumsalts; halogen compounds; combinations of organic metal andorganohalogen; benzoin and o-nitrobenzyl esters of a strong acid such astoluene sulfonic acid; and N-hydroxyamide and N-hydroxyimide sulfonatesas described in U.S. Pat. No. 4,371,605, and also includeallylnaphthoquinone-diazide-4-sulfonates. A preferablephoto-solubilizing agent is diaryliodonium or triarylsulfonium salts. Ingeneral, these compounds present in the form of the salts of complexmetal halide ions, such as tetrafluoropoloate, hexafluoroantimonate,hexafluoroarsenate, and hexafluorophosphate. Other effective groups ofacid generators exhibiting photosensitivity include oligomers andpolymers, to which an anionic group having an aromatic onium acidgenerator as positive pair ions is added. Examples of such polymersinclude polymers described at column 9, lines 1 to 68, and column 10,lines 1 to 14 in U.S. Pat. No. 4,661,429, the teaching of which arehereby incorporated by reference. For the purpose of controlling aspectrum sensitivity to an applicable wavelength of actinic rays, asensitizer is preferably added to the system. Necessity of addition of asensitizer depends on requirements of the system and a specificphotosensitive compound to be used. For example, in the case of iodoniumand sulfonium salts which respond to only a wavelength less than 300 nm,use of benzophenone and derivatives thereof, polycyclic aromatichydrocarbons such as perylene, pyrene and anthracene, and derivativesthereof makes it possible to be photosensitive to a longer wavelength.The decomposition of diaryliodonium and triarylsulfonium salts is alsomade photosensitive by the use ofbis-(p-N,N-dimethylaminobenzylidene)-acetone. A sulfonium salt bonded toanthracene via a chain comprising 3 to 4 atoms is an effectivephoto-solubilizing agent. Compounds described in MG. Tilley'sdissertation for a Ph.D, North Dakota State University, Fargo, N. Dak.(1988) “Diss. Abstr. Int. B, 49, 8791 (1989): Chem. Abstr., 111, 39942u”are preferable type photo-solubilizing agents. As another preferableacid generator, ATASS, that is,3-(9-anthracenyl)propyl-diphenylsulfonium-hexafluoroantimonate can bementioned.

In this compound, anthracene and a sulfonium salt are bonded via a chaincomprising 3 carbons. Additional examples of acid generators to hereinbe used include diphenyliodonium tosylate, benzoin tosylate, andtriarylsulfonium hexafluoroantimonate. As acid generators other than theacid generators mentioned above, iron-arene complexes, ruthenium-arenecomplexes, silanol-metal chelate complexes, triazine compounds,diazidonaphthoquinone compounds, sulfonates, imidosulfonates, andhalogen-based compounds can also be used, for example. In addition, acidgenerators described in Japanese Patent Laid-open No. Hei 7-146552 andJapanese Patent Application No. Hei 9-289218 can also be used. Themixing ratio of the acid generator is preferably in a range of about 0.1to 40 parts by weight, particularly about 0.2 to 20 parts by weight withrespect to 100 parts by weight of the total of the compound (A) and theresin (B). As a positive resin composition for activation energy rays tobe used for a dry film of the present invention, an organicsolvent-based resin composition obtained by dispersing or dissolving theabove-described components (in a case where a pigment is used as acolorant, the pigment is finely dispersed) in an organic solvent can beused.

The composition of the present invention contains three components, thevinyl ether group-containing compound (A), the polymer (B), and asnecessary, the photo-acid generating compound (C). Although the mixingratio among them may vary within a wide range depending on applicationsof the composition, a preferred amount of the vinyl ethergroup-containing compound (A) to be used is usually in a range of 5 to150 parts by weight, particularly in a range of 10 to 100 parts byweight with respect to 100 parts by weight of the polymer (B), and apreferred amount of the photo-acid generating compound to be used isusually in a range of 0 to 40 parts by weight, particularly in a rangeof 0.2 to 20 parts by weight with respect to 100 parts by weight of thetotal amount of the polymer (B) and the vinyl ether group-containingcompound (A).

The composition of the present invention may contain a sensitizing dye,as necessary. Examples of a usable sensitizing dye include dyes such asphenothiazine type, anthracene type, coronene type, benzanthracene type,perylene type, pyrene type, merocyanine type, and ketocoumarin type.

A range of the amount of the sensitizing dye to be mixed is 0.1 to 10parts by weight, preferably 0.3 to 5 parts by weight with respect to 100parts by weight of the polymer (B).

The composition of the present invention may contain a colorant, asnecessary. As a usable colorant, a combination of a leuco dye and ahalogen compound is well known. Examples of a leuco dye includetris(4-dimethylamino-2-methylphenyl)methane “leuco crystal violet” andtris(4-dimethylamino-2-methylphenyl)methane “leuco malachite green”. Onthe other hand, examples of a halogen compound include amyl bromide,isoamyl bromide, isobutylene bromide, ethylene bromide, diphenylmethylbromide, benzayl bromide, methylene bromide,tribromomethylphenylsulfone, carbon tetrabromide,tris(2,3-dibromopropyl)phosphate, trichloroacetamide, amyl iodide,isobutyl iodide, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, andhexachloroethane. The composition may contain a colorant other than thecolorants mentioned above.

For the purpose of imparting appropriate flexibility and non-tackinessto the formed film, the composition of the present invention may containa plasticizer such as phthalate ester; a polyester resin; or an acrylicresin. In usual, the content of them is preferably 50 parts by weight orless with respect to 100 parts by weight of the total amount of thepolymer (B) and the vinyl ether group-containing compound (A).

Further, the composition of the present invention may contain afluidity-controlling agent, as necessary.

The composition of the present invention can be prepared by mixing theabove-mentioned components as they are, or mixing them in a solvent, asnecessary. A usable solvent is not particularly limited as long as itcan dissolve the components of the composition. Examples of such asolvent include: ketones such as acetone, methyl ethyl ketone, methylisobutyl ketone, cyclohexanone, and isophorone; esters such as methylacetate, ethyl acetate, and butyl acetate; C₁ to C₁₀ aliphatic alcoholssuch as methanol, ethanol, and propanol; aromatic groupcontaining-alcohols such as benzyl alcohol; glycols such as ethyleneglycol and propylene glycol; glycol ethers such as mono- or diethers ofthese glycols with methanol, ethanol, butanol, hexanol, octanol, benzylalcohol, or phenol, or esters of the monoethers; cyclic ethers such asdioxane and tetrahydrofuran; cyclic carbonates such as ethylenecarbonate and propylene carbonate; and aliphatic or aromatichydrocarbons. These solvents can be used singly or in combination of twoor more, as necessary.

It is to be noted that the present invention has a feature that an atomat the bonding site of the vinyl ether group of the vinyl ethergroup-containing compound is a secondary or tertiary carbon atom. As aresult, it is believed that the cross-linked structure formed by anaddition reaction between a carboxyl group or a hydroxyphenyl group anda vinyl ether group is easily cleaved by an acid generated byirradiation with light or exposure by carrying out a heat treatment at atemperature less than 60° C. or carrying out no heat treatment, therebyenabling a resist pattern having an excellent sensitivity and resolutionto be formed.

Next, a method of forming a pattern of the present invention will bedescribed.

Pattern Formation Method 1:

One embodiment of a pattern formation method of the present inventioncomprises the steps of: applying the composition for activation energyrays onto a substrate; heating the substrate; irradiating the substratewith activation energy rays for patterning; carrying out no heattreatment or carrying out a heat treatment at a temperature less than60° C. after irradiation; and developing the substrate with a basicdeveloper. By carrying out these steps in order, a desired resistpattern can be formed.

Pattern Formation Method 2:

Another embodiment of the pattern formation method of the presentinvention comprises the steps of: applying the composition foractivation energy rays onto a transparent support film capable oftransmitting activation energy rays and drying it to form a film layerof the composition for activation energy rays, obtaining a dry filmresist for activation energy rays; press-bonding the film layer foractivation energy rays of the dry film resist onto a substrate on whicha pattern is to be formed; heating the substrate; irradiating the filmlayer with activation energy rays through the support film forpatterning; carrying out a heat treatment at a temperature less than 60°C. or carrying out no heat treatment after irradiation; and removing thesupport film and developing the substrate with a basic developer. Bycarrying out these steps in order, a desired resist pattern can beformed.

Pattern Formation Method 3:

Still another embodiment of the pattern formation method of the presentinvention comprises the steps of: applying the composition foractivation energy rays onto a transfer film and drying it to form a filmlayer of the composition for activation energy rays, obtaining atransfer film resist; press-bonding the film layer of the compositionfor activation energy rays of the transfer film resist onto a substrateon which a pattern is to be formed; heating the substrate; removing thetransfer film; irradiating the film layer with activation energy raysfor patterning; carrying out a heat treatment at a temperature less than60° C. or carrying out no heat treatment after irradiation; anddeveloping the substrate with a basic developer. By carrying out thesesteps in order, a desired resist pattern can be formed.

Articles and methods to be used in these steps in the pattern formationmethods 1 to 3 will be described below.

As a substrate onto which the composition for activation energy rays isto be applied, or the dry film resist or the transfer film resist is tobe press-bonded, a copper-clad laminate can be used, for example.

The composition for activation energy rays can be applied onto asubstrate or a support film which will be described later by means suchas a roller, a roll coater, a spin coater, a curtain-roll coater,spraying, electrostatic coating, dip coating, silk printing, or spincoating.

The substrate or the support film onto which the composition foractivation energy rays has been applied is heated in a hot air drier at60 to 150° C. for 5 minutes to 1 hour, preferably at 80 to 120° C. for10 to 30 minutes, thereby forming a coating film.

A light source for irradiation with activation energy rays to form apattern may be a light within a visible region obtained by cuttingultraviolet rays through a UV-cutting filter from a light obtained froma conventionally used light source such as an ultra-high, high,moderate, or low pressure mercury lamp, a chemical lamp, a carbon arclamp, a xenon lamp, a metal halide lamp, a fluorescent lamp, a tungstenlamp, or solar light, or various lasers having an oscillation linewithin a visible region. As a high power and stable laser beam source,an argon laser or the second harmonic of a YAG laser (532 nm) ispreferable.

In the liquid developing treatment, for example, spraying or dipping maybe carried out using a developer having a temperature of about 10 to 80°C., preferably about 15 to 50° C. for about 10 seconds to 60 minutes,preferably about 30 seconds to 30 minutes, thereby enabling a pattern tobe formed on the film layer of the composition for activation energyrays.

Examples of the liquid developer include an aqueous solution ofmonomethylamine, dimethylamine, trimethylamine, monoethylamine,diethylamine, triethylamine, monoisopropylamine, diisopropylamine,triisopropylamine, monobutylamine, dibutylamine, monoethanolamine,diethanolamine, triethanolamine, dimethylaminoethanol,diethylaminoethanol, ammonia, sodium hydroxide, potassium hydroxide,sodium metasilicate, potassium metasilicate, sodium carbonate, ortetraethylammonium hydroxide.

As a transparent support film capable of transmitting activation energyrays, which is to be used for the dry film resist in the patternformation method (2) of the present invention, polyethyleneterephthalate can be used.

The film layer for activation energy rays of the dry film resist can bepress-bonded onto a substrate, on which a resist pattern is to beformed, while applying pressure at a temperature of 30 to 120° C., forexample.

As a transfer film to be used for the transfer film resist in thepattern formation method (3) of the present invention, polyethyleneterephthalate can be used, for example.

The film layer of the composition for activation energy rays of thetransfer film resist can be press-bonded onto a substrate while applyingpressure at a temperature of 30 to 120° C., for example.

In the pattern formation methods (2) and (3), the resist filmpress-bonding step and the substrate heating step may be carried outseparately, or they may be carried out simultaneously at press-bonding,as described above.

The composition of the present invention can be used for variouspurposes such as paint, ink, adhesives, resist materials, printing platematerials (materials for surface printing plates or relief printingplates, or PS plates for offset printing), information recordingmaterials, and materials for forming relief images, similarly to knownphotosensitive materials.

The method of the present invention can be applied to any purposewithout limitation as long as the method comprises the above-mentionedsteps.

Examples of the purposes organized by industrial fields include:electrical fields such as electrical parts, lightings, electricaldevices, semiconductors, printings, printed circuits, electroniccommunications, and electric powers; physical fields such as measurementfield, optical field, display field, acoustic field, control field,vending field, signals, and information recording field;chemistry/metallurgy/fiber fields such as inorganic chemistry, organicchemistry, polymer chemistry, metallurgy, and fiber;treatment/transportation fields such as separation or mixing, metalprocessing, plastic processing, printings, containers, and packing;articles for living such as agricultural and marine fields, foods,fermentation, household articles, health and recreation fields; andmechanical engineering.

Examples of the electrical fields include a black matrix insulating filmformation method, an insulating film formation method by build upmethod, a solder resist insulating film formation method, a displaypanel barrier formation method, a formation method of a black belt for adisplay panel, a formation method of a colored insulating film for acolor filter, a display panel fluorescent material, a hologram pattern,CD mastering, and coil; examples of the physical fields include opticalfiber fabricating, floppy disk, magnetic tape, magnetic card, opticalparts, and electric wave absorber; examples ofchemistry/metallurgy/fiber fields include inorganic glass, cement, andceramic insulators; examples of treatment/transportation fields includeprinted matter, printing original plate, diffraction grating, marking,bar code, mask, filter, etching, defroster, cement processing, stoneprocessing, fiber processing, plastic processing, and label; examples ofarticles for living include carrier, cosmetic, and fermentationindustry; and examples of mechanical engineering include micromachineparts.

The present invention is not limited to the following examples. In thefollowing description, “part” and “%” are “part by weight” and “% byweight”, respectively.

Synthesis Example 1

Synthesis of a carboxyl group-containing polymer (1)

A mixture containing 7.8 parts of acrylic acid, 50 parts of methylmethacrylate, 12.2 parts of ethyl acrylate, 30 parts of phenoxyethyleneglycol acrylate, and 1 part of tert-butylperoxy-2-ethylhexanoate as apolymerization initiator was polymerized to obtain a carboxylgroup-containing polymer. The obtained carboxyl group-containing polymerhad a number-average molecular weight of 4,500, a carboxyl group contentof 1 equivalent/kg of polymer, and a glass transition temperature of 0°C. or higher.

Synthesis Example 2

Synthesis of Hydroxyphenyl Group-Containing Polymer (2)

1,490 parts of o-cresol, 1,145 parts of a 30% aqueous formaldehydesolution, 130 parts of deionized water, and 6.5 parts of oxalic acidwere placed into a flask, and the mixture was refluxed for 60 minutes.13.5 parts of 15% hydrochloric acid was added thereto, and the resultingmixture was refluxed for 40 minutes. 400 parts of deionized water havinga temperature of about 15° C. was added thereto, and the contents in theflask were kept at about 75° C. to precipitate a resin. A 35% sodiumhydroxide solution was added thereto for neutralization, and then anaqueous layer was removed. The same washing operation was repeatedtwice, and then the resin was dried at about 120° C. under reducedpressure to obtain a novolac phenol resin. The obtained novolac phenolresin (hydroxyphenyl group-containing polymer) had a number-averagemolecular weight of 600, a hydroxyphenyl group content of 10equivalents/kg of polymer, and a glass transition temperature of 0° C.or higher.

Synthesis Example 3

Synthesis of Carboxyl Group and Hydroxyphenyl Group-Containing Polymer(3)

600 parts of o-hydroxybenzoic acid, 900 parts of o-cresol, 1,145 partsof a 30% aqueous formaldehyde solution, 130 parts of deionized water,and 6.5 parts of oxalic acid were placed into a flask, and the mixturewas refluxed for 60 minutes. 13.5 parts of 15% hydrochloric acid wasadded thereto, and the resulting mixture was refluxed for 40 minutes.400 parts of deionized water having a temperature of about 15° C. wasadded thereto, and the contents in the flask were kept at about 50° C.to precipitate a resin. 400 parts of deionized water was added theretoto wash the resin at 50° C., and an aqueous layer was then removed. Thesame washing operation was repeated three times, and the resin was driedat about 120° C. under reduced pressure to obtain a novolac phenol resin(3). The obtained novolac phenol resin had a number-average molecularweight of about 650, a carboxyl group content of 2.8 mols/kg of polymer,a hydroxyphenyl group content of 5.4 mols/kg of polymer, and a glasstransition temperature of 0° C. or higher.

Example 1

A mixture containing a resin obtained by adding 100 parts of the polymer(1) as the polymer (B) to 14 parts of cyclohexyl vinyl ether as thevinyl ether group-containing compound (A), and 2 parts of a photo-acidgenerator (available from DAICEL UCB CO LTD under the name of“UVAC1591”, and hereinafter this product was used as a photo-acidgenerator) was dissolved in cyclohexanone to prepare a 30 wt %composition solution.

Example 2

A 30 wt % composition solution was prepared in the same manner asExample 1 except that the polymer (2) was used as the polymer (B).

Example 3

A 30 wt % composition solution was prepared in the same manner asExample 1 except that the polymer (3) was used as the polymer (B).

Comparative Example 1

A 30 wt % composition solution was prepared in the same manner asExample 1 except that methyl vinyl ether was used as the vinyl ethergroup-containing compound (A).

Example 4

A mixture containing 100 parts of the polymer (1) as the polymer (B), 53mmol of a compound represented by the following formula as the vinylether group-containing compound (A) with respect to 100 g of the polymer(1), and 2 parts of the photo-acid generator was dissolved incyclohexanone, to prepare a 30 wt % composition solution:

Example 5

A 30 wt % composition solution was prepared in the same manner asExample 4 except that the polymer (2) was used as the polymer (B).

Example 6

A 30 wt % composition solution was prepared in the same manner asExample 4 except that the polymer (3) was used as the polymer (B).

Example 7

A mixture containing 100 parts of the polymer (1) as the polymer (B), 53mmol of a compound represented by the following formula as the vinylether group-containing compound (A) with respect to 100 g of the polymer(1), and 2 parts of the photo-acid generator was dissolved incyclohexanone, to prepare a 30 wt % composition solution:

Example 8

A 30 wt % composition solution was prepared in the same manner asExample 7 except that the polymer (2) was used as the polymer (B).

Example 9

A 30 wt % composition solution was prepared in the same manner asExample 7 except that the polymer (3) was used as the polymer (B).

Comparative Example 2

A 30 wt % composition solution was prepared in the same manner asExample 4 except that a compound represented by the following formulawas used as the vinyl ether group-containing compound (A):

Comparative Example 3

A 30 wt % composition solution was prepared in the same manner asExample 4 except that a compound represented by the following formuladescribed in Example 1 of Japanese Patent Laid-open No. Hei 6-295064 wasused as the vinyl ether group-containing compound (A):

Performance Evaluation Test 1:

A resist film was formed using the composition solution of each ofExamples and Comparative Examples and its performance was evaluated asfollows. The resist film was formed by applying the solution obtained ineach of Examples and Comparative Examples onto a copper-clad substrateto have a dry film thickness of 10 μm by the use of a bar coater, anddrying the applied solution at 100° C. for 10 minutes to carry out anaddition reaction of a carboxyl group or a hydroxyphenyl group with avinyl ether group.

(1) Drying Properties after Pre-Drying Evaluated by Touching with aFinger

After drying the applied composition solution of each of Examples andComparative Examples, the drying properties of the coating film surfacewere determined by touching with the finger and evaluated according tothe following criteria.

O: Tackiness was not observed at all.

Δ: Tackiness was slightly observed.

X: Tackiness was considerably observed.

(2) Sensitivity

After drying the applied composition solution of each of Examples andComparative Examples, the obtained resist film was irradiated withultraviolet rays of 365 nm through a 21-step step tablet (manufacturedby HITACHI), and was then allowed to stand at room temperature for 10minutes. Then, the resist film was developed using an aqueous 0.75%sodium carbonate solution having a temperature of 25° C., to prepare atest substrate. For Examples 1 to 3 and Comparative Example 1,irradiation was carried out at an ultraviolet rays intensity of 300mJ/cm², 500 mJ/cm², and 1,000 mJ/cm², and for Examples 4 to 9 andComparative Examples 2 and 3, irradiation was carried out at anultraviolet rays intensity of 100 mJ/cm², 300 mJ/cm², and 1,000 mJ/cm².Sensitivity was evaluated according to the number of steps of the steptablet that a pattern could be formed.

(3) Resistance to Etching

Each of the test substrates prepared in the same manner described abovewas subjected to etching using a cupric chloride etching solution, andthe test substrate was visually checked as to whether or not the coatingfilm was stripped. Evaluation was carried out according to the followingcriteria.

O: Stripping was not observed at all.

A: Stripping was slightly observed.

X: Stripping was considerably observed.

(4) Separation Properties

Each of the test substrates prepared in the same manner described abovewas dipped in a 3% aqueous sodium hydroxide solution at 50° C., and thenthe test substrate was visually observed to check the removability andseparation properties of the coating film. Evaluation was carried outaccording to the following criteria.

O: No resist residues were observed.

A: Resist residues were slightly observed.

X: Resist residues remained all over the surface of the substrate.

The results of the above tests are shown in Table 1. As is apparent fromTable 1, the coating film formed from the compound for activation energyrays of the present invention has excellent sensitivity, high resistanceto etching, and an excellent separation properties.

TABLE 1 Performance evaluation Drying properties evaluated Resistance bytouching Sensitivity (mJ/cm²) to Separation with finger 100 300 5001,000 etching properties Ex. 1 ◯ — 7 steps 10 steps  14 steps ◯ ◯ Ex. 2◯ — 5 steps 8 steps 12 steps ◯ ◯ Ex. 3 ◯ — 6 steps 9 steps 13 steps ◯ ◯Comp. ◯ — Exposed Exposed Exposed ◯ ◯ Ex. 1 portions portions portionswere were were insoluble insoluble insoluble Ex. 4 ◯ 7 steps 10 steps  —14 steps ◯ ◯ Ex. 5 ◯ 5 steps 8 steps — 12 steps ◯ ◯ Ex. 6 ◯ 6 steps 9steps — 13 steps ◯ ◯ Ex. 7 ◯ 7 steps 10 steps  — 14 steps ◯ ◯ Ex. 8 ◯ 5steps 8 steps — 12 steps ◯ ◯ Ex. 9 ◯ 6 steps 9 steps — 13 steps ◯ ◯Comp. ◯ Exposed Exposed — Exposed ◯ ◯ Ex. 2 portions portions portionswere were were insoluble insoluble insoluble Comp. ◯ Exposed Exposed —Exposed ◯ ◯ Ex. 3 portions portions portions were were were insolubleinsoluble insoluble

Example 10

The composition solution obtained in Example 1 was applied onto anon-treated polyethylene terephthalate support film with a thickness of38 μm to have a dry film thickness of 10 μm by the use of a roll coater,and was dried at 120° C. for 10 minutes. Then, a non-treatedpolypropylene film having a thickness of 20 μm was attached to thecoating film surface to prepare a dry film resist.

After the polypropylene film was removed, the coating film surface ofthe dry film resist was press-bonded onto a substrate obtained bylaminating a copper film with a thickness of 18 μm onto a polyimide filmwith a thickness of 100 μm, by the use of a laminator with a rolltemperature of 100° C.

The obtained substrate was exposed in the same manner as Performanceevaluation test 1, and was then allowed to stand at room temperature for10 minutes. After the support film was removed, evaluation was carriedout in the same manner as Performance evaluation test 1. The results areshown in Table 2.

Example 11

The composition solution obtained in Example 1 was applied onto anon-treated polyethylene terephthalate transfer film with a thickness of38 μm to have a dry film thickness of 10 μm by the use of a roll coater,and was dried at 120° C. for 10 minutes, to prepare a transfer filmresist.

The transfer film resist was press-bonded onto a substrate obtained bylaminating a copper film with a thickness of 18 μm onto a polyimide filmwith a thickness of 100 μm, by the use of a laminator with a rolltemperature of 100° C.

After the transfer film was removed, the substrate was exposed in thesame manner as Performance evaluation test 1, and was then allowed tostand at room temperature for 10 minutes. Thereafter, evaluation wascarried out in the same manner as Performance evaluation test 1. Theresults are shown in Table 2.

Example 12

A dry film resist was prepared and evaluated in the same manner asExample 10 except that the composition solution obtained in Example 4was used. The results are shown in Table 2.

Example 13

A transfer film type resist was prepared and evaluated in the samemanner as Example 11 except that the composition solution obtained inExample 4 was used. The results are shown in Table 2.

Example 14

A dry film resist was prepared and evaluated in the same manner asExample 10 except that the composition solution obtained in Example 7was used. The results are shown in Table 2.

Example 15

A transfer film type resist was prepared and evaluated in the samemanner as Example 11 except that the composition solution obtained inExample 7 was used. The results are shown in Table 2.

TABLE 2 Performance evaluation Drying properties evaluated Resistance bytouching Sensitivity (mJ/cm²) to Separation with finger 100 300 5001,000 etching properties Ex. 10 ◯ — 7 steps 10 steps 14 steps ◯ ◯ Ex. 11◯ — 7 steps 10 steps 14 steps ◯ ◯ Ex. 12 ◯ 5 steps 8 steps — 12 steps ◯◯ Ex. 13 ◯ 7 steps 10 steps  — 14 steps ◯ ◯ Ex. 14 ◯ 5 steps 8 steps —12 steps ◯ ◯ Ex. 15 ◯ 7 steps 10 steps  — 14 steps ◯ ◯

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, it is possibleto provide a chemically amplified positive resist having an excellentsensitivity and resolution even in conditions that heating at atemperature less than 60° C. is carried out or heating is not carriedout after exposure, thereby enhancing production speed and improving thereliability of the resist. Since heating after exposure is not necessaryor carried out at a low temperature, thermal history to a substrate canbe controlled, reducing thermal effects on the substrate. In addition, acapital investment and an energy cost associated with heating afterexposure can be reduced.

1. A composition for activation energy rays comprising, as essentialcomponents, a vinyl ether group-containing compound (A) represented bythe following formula:

and at least one polymer (B) selected from the group consisting of thefollowing polymers (a) to (c); (a) a polymer containing 0.5 to 10equivalents of a carboxyl group per kg of the polymer, and having anumber-average molecular weight in a range of 3,000 to 100,000 and aglass transition temperature of 0° C. or higher, (b) a polymercontaining at least 1 to 10 equivalents of a hydroxyphenyl group per kgof the polymer, and having a number-average molecular weight in a rangeof 500 to 100,000 and a glass transition temperature of 0° C. or higher,and (c) a polymer containing at least 0.2 to 20 equivalents of ahydroxyphenyl group and a carboxyl group per kg of polymer, and having anumber-average molecular weight in a range of 500 to 100,000 and a glasstransition temperature of 0° C. or higher.